Orbital fitting of Fomalhaut b and subsequent interaction with the dust belt

Hervé Beust, Virginie Faramaz, Jean Charles Augereau

Research output: Contribution to journalArticlepeer-review


Fomalhaut harbours a moderately eccentric dust belt with a planet candidate (Fom b) imaged near its inner edge. MCMC-based orbital determination of Fom b shows that the orbit is highly eccentric (e≃0.9), nearly apsidally aligned with the belt. We study the secular interaction between the planet and the dust ring. We show that only if it is a small mass object, Fom b can perturb the belt without destroying it. But Fom b's perturbing action inevitably drives the belt to high eccentricity and apsidal misalignment. This behaviour is due to the planet's high eccentricity. This dynamical outcome contradicts both observations and orbital determination. We conclude that another, more massive and less eccentric planet (Fom c) is required to dynamically control the belt. We show that Fom b is likely to have been formerly trapped in mean-motion resonance with Fom c and that subsequent eccentricity increase caused it to cross Fom c's orbit and to jump on its present day orbit via a scattering event.

Original languageEnglish (US)
Pages (from-to)78-81
Number of pages4
JournalProceedings of the International Astronomical Union
StatePublished - 2014
Externally publishedYes


  • Celestial mechanics
  • Methods: numerical
  • Planet-disk interactions
  • Planetary systems
  • Stars: Fomalhaut

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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